Polymorphic transformations in iron and zirconium

Polymorphic transformations in iron of differing purity and zirconium iodide have been studied by the high-resolution calorimetry method. The hypothesis has been made that polymorphic transformations in zirconium, unlike those in iron, are governed by two mechanisms–diffusionless and diffusion. Which of them prevails depends on the temperature cycling rate and thermal history of the zirconium.